(Table) Argon isotope ratios and argon ages of rocks obtained from the Chernorud zone, western Baikal area

Structural-petrologic and isotopic-geochronologic data on magmatic, metamorphic, and metasomatic rocks from the Chernorud zone were used to reproduce the multistage history of their exhumation to upper crustal levels. The process is subdivided into four discrete stages, which corresponded to metamorphism to the granulite facies (500-490 Ma), metamorphism to the amphibolite facies (470-460 Ma), metamorphism to at least the epidote-amphibolite facies (440-430 Ma), and postmetamorphic events (410-400 Ma). The earliest two stages likely corresponded to the tectonic stacking of the backarc basin in response to the collision of the Siberian continent with the Eravninskaya island arc or the Barguzin microcontinent, a process that ended with the extensive generation of synmetamorphic granites. During the third and fourth stages, the granulites of the Chernorud nappe were successively exposed during intense tectonic motions along large deformation zones (Primorskii fault, collision lineament, and Orso Complex). […]

本研究利用采自切尔诺鲁德带（Chernorud Zone）的岩浆岩、变质岩及交代岩的构造岩石学与同位素地质年代学数据，重建了这些岩石折返至上地壳深度的多期演化历史。该折返过程可划分为四个独立阶段，分别对应麻粒岩相变质作用（500~490 Ma）、角闪岩相变质作用（470~460 Ma）、至少绿帘角闪岩相变质作用（440~430 Ma）以及变质后事件（410~400 Ma）。前两期变质作用大概率对应西伯利亚大陆与埃拉文宁斯卡亚岛弧（Eravninskaya Island Arc）或巴尔古津微大陆（Barguzin Microcontinent）碰撞引发的弧后盆地构造堆叠作用，该过程以同变质花岗岩的大规模形成而告终。在第三、第四阶段，切尔诺鲁德推覆体（Chernorud Nappe）的麻粒岩随着沿大型变形带（普里莫尔斯基断层（Primorskii Fault）、碰撞构造线及奥尔索杂岩（Orso Complex））的强烈构造运动而依次出露地表。[…]